Live multitracking

Hey guys, recently I tried recording 32 tracks of live audio simultaneously into my Mac mini (specs listed below) and was unable to capture more than 17 before Logic X told me my disk was too slow. Now, I've done the research and I've ordered an external hard drive that spins at 7200rpm and is powered by USB 3.0 and/or Thunderbolt, as this was what has been recommended to me. I was just wondering, would Bus powered drives have a harder time than a drive with its own dedicated power supply? Also, do transfer rates have any huge effect on the multitracking process? The drive I ordered says it gets about 130mbps but I wasn't sure if that will effect my recording performance much or not, if so I'd like to find another drive.

Any and all responses would be greatly appreciated as I do not want to waste time or money on a device that isn't going to help me accomplish my goal. Thanks so much!

Sorry, no hands-on experience here, just two hints:

Bus-powering won't reduce transfer rates, there are separate lines for that in your cable.

And here is a simple calculation: Assuming you record 32 channels with a bit depth of 16 bits and a sample rate of 44100 samples per second you will end up with about 23 megabits per second (and proportionally more for higher bit depths/sample rates). 130mbps should be enough, but is it really write speed? Is it peak (as long as the HD's cache isn't filled completely) or continuous?

Recorded 32 live tracks with a 7200 bus powered USB 3 drive.

Not a hiccup.